This invention relates to barriers in general and, in particular, to traffic barriers.
Traffic barriers separate lanes of automobile traffic. Such barriers find particular use in separating lanes of oppositely flowing traffic, although they are also useful for separating lanes of traffic flowing in the same direction and for separating traffic from pedestrians or from dangerous conditions along the road.
One particular application of traffic barriers is in separating lanes of traffic on bridges. To make optimum use of the limited width, bridges often have little or no space between oppositely flowing lanes of traffic, thereby creating a potentially dangerous situation. Placing traffic barriers between the oppositely directed traffic lanes minimizes this danger.
Prior art bridge traffic barriers fall into two categories: permanent barriers and movable barriers. Because they may be firmly attached to the bridge surface, permanent barriers are more resistant to vehicle impacts and therefore tend to be more effective traffic separators than movable barriers. One drawback to permanent barriers, however, is their immobility. To make optimum use of the limited number of lanes on a bridge, traffic engineers may change the direction of the flow on one or more of the bridge lanes to accommodate the vehicle traffic demand. Thus, permanent barriers are effective for separating oppositely flowing traffic only if the direction of the traffic flow remains the same for the lanes on either side of the barrier.
Movable barriers are one solution to the problem of separating traffic flow on bridge lanes with changeable traffic flow directions. Such barriers may be moved from one lane to another as the traffic flow demands. Prior art movable barriers, however, suffer from two major deficiencies. First, movable barriers must provide vertical stability in order to withstand vehicle impacts. Prior art movable barriers therefore usually have a wide base resting against the bridge road surface. This wide base is unacceptable on most bridges where vehicle space is at a premium. What is needed, therefore, is a movable barrier whose width does not interfere with vehicle traffic on either side of the barrier.
The second deficiency of prior art movable barriers is the relatively long time it takes for bridge workers to move the barriers from one lane to another. The process of moving the barriers often requires the closing of two lanes of traffic, an undesirable situation on busy bridges. What is needed, therefore, is a movable barrier design which reduces the moving time and minimizes the disruption of traffic flow on the bridge during the move.